Question

blood vessels
there are three main blood vessels: arteries, capillaries, and veins. arteries are thick muscular vessels that carry blood away from the heart. when you take your pulse you are touching an artery. the aorta is your main artery. capillaries are very tiny - they are the thickness of one strand of hair. diffusion of materials occurs through the wall of the capillaries. gas exchange, nutrient exchange, and waste exchange occur through the capillaries. veins carry blood back to the heart. they contain valves that prevent the backflow of blood due to gravity. the main vein in the body is the vena cava.
assessment question#2
the diagrams below represent cross sections of vessels found in the human circulatory system.
diagram a most likely represents
a. vein b. lymph vessel c. capillary d. artery

Explanation:

To determine what Diagram A represents, we analyze the characteristics of blood vessels:

• Arteries are described as thick muscular vessels. Diagram A has a thick wall and a circular cross - section, which matches the structure of an artery.
• Veins have thinner walls and valves (not shown in Diagram A's structure here) and a more flattened cross - section (like Diagram B), so A is not a vein.
• Lymph vessels have a different structure and function compared to the blood vessels in the question, and Diagram A does not match lymph vessel structure.
• Capillaries are very tiny (thickness of one hair strand), and Diagram A is relatively large, so it is not a capillary.

Answer:

d. artery